From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 88BA06B01F0 for ; Fri, 14 May 2010 02:23:48 -0400 (EDT) Received: by pva4 with SMTP id 4so1063708pva.14 for ; Thu, 13 May 2010 23:23:47 -0700 (PDT) Date: Fri, 14 May 2010 14:27:34 +0800 From: =?utf-8?Q?Am=C3=A9rico?= Wang Subject: Re: /proc//maps question....why aren't adjacent memory chunks merged? Message-ID: <20100514062734.GA5612@cr0.nay.redhat.com> References: <4BEC704C.9000709@nortel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4BEC704C.9000709@nortel.com> Sender: owner-linux-mm@kvack.org To: Chris Friesen Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Thu, May 13, 2010 at 03:34:04PM -0600, Chris Friesen wrote: >Hi, > >I've got a system running a somewhat-modified 2.6.27 on 64-bit x86. > >While investigating a userspace memory leak issue I noticed that >/proc//maps showed a bunch of adjacent anonymous memory chunks with >identical permissions: > >7fd048000000-7fd04c000000 rw-p 00000000 00:00 0 >7fd04c000000-7fd050000000 rw-p 00000000 00:00 0 >7fd050000000-7fd054000000 rw-p 00000000 00:00 0 >7fd054000000-7fd058000000 rw-p 00000000 00:00 0 >7fd058000000-7fd05c000000 rw-p 00000000 00:00 0 >7fd05c000000-7fd060000000 rw-p 00000000 00:00 0 >7fd060000000-7fd064000000 rw-p 00000000 00:00 0 >7fd064000000-7fd068000000 rw-p 00000000 00:00 0 >7fd068000000-7fd06c000000 rw-p 00000000 00:00 0 >7fd06c000000-7fd070000000 rw-p 00000000 00:00 0 >7fd070000000-7fd074000000 rw-p 00000000 00:00 0 >7fd074000000-7fd078000000 rw-p 00000000 00:00 0 >7fd078000000-7fd07c000000 rw-p 00000000 00:00 0 >7fd07c000000-7fd07fffe000 rw-p 00000000 00:00 0 > >I was under the impression that the kernel would merge areas together in >this circumstance. Does anyone have an idea about what's going on here? > Well, that is not so simple, there are other considerations, you need to check vma_merge(), especially can_vma_merge_{after,before}(). Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org